Rajesh, his wife Sangita (33) and son Pratik (4) lived in a rented room of an old building which was in a dilapidated condition, police said.
The police received information about the incident at around 9 PM. Sangita and Pratik were sleeping when a heavy chunk of plaster fell on them while Rajesh had gone to work when the tragedy occurred.
They were rushed by the neighbours to a nearby hospital where the doctors declared Pratik dead while Sangita was discharged after treatment.